1. Field of the Invention
The present invention relates generally to image forming apparatuses such as copiers, printers, facsimile machines, and multifunction machines thereof. Among them, the present invention relates to an electrophotographic image forming apparatus. In the electrophotographic image forming apparatus, charging, writing, and development are performed to form a toner image on an image carrier. The toner image is directly transferred or indirectly transferred via an intermediate transfer member and then fixed by a fixing device. In this manner, the electrophotographic image forming apparatus records an image on a recording member such a paper. In particular, the present invention relates to the image forming apparatus including the fixing device that fixes toner particles on a recording member using a toner fixing liquid.
In addition, the present invention relates to a replacement unit that accommodates toner particles and a toner fixing liquid as consumable supplies and is replaceably provided in an image forming apparatus main body including such a fixing device. Furthermore, the present invention relates to a method of attaching the replacement unit to the image forming apparatus main body.
2. Description of the Related Art
Image forming apparatuses such as printers, facsimile machines, and copiers record images including, characters, symbols, etc., on recording members such as papers, clothes, and OHP films based on image information. Among various types of such image forming apparatuses, an electrophotographic image forming apparatus is widely used in offices because it can record high-definition images on plain paper at high speed.
The electrophotographic image forming apparatus has a charging device, a writing device, a development device, a transfer device, a cleaning device, a static elimination device, etc., around a drum-like or belt-like image carrier. In the electrophotographic image forming apparatus, the image carrier is charged as it is rotated and then subjected to writing so as to form an electrostatic latent image on its front surface. Subsequently, the electrostatic latent image is developed with the adhesion of toner particles to form a toner image on the image carrier. After this, the toner image is directly transferred or indirectly transferred via a belt-like intermediate transfer member or the like to a recording member. In this manner, an image is recorded on the recording member. The recording member having the toner image transferred thereon is introduced into a fixing device. In the fixing device, unfixed toner particles are fixed onto the recording member, while the front surface of the image carrier is cleaned by the cleaning device and static electricity is eliminated from the front surface so as to be ready for the next image formation.
In the electrophotographic image forming apparatus of this type, a fixing device of a heat fixing system is widely used because it provides a fast fixing speed and excellent fixed-image quality. According to the fixing device of the heat fixing system, toner particles on a recording member are heated and dissolved by a heat generator such as a halogen heater or a ceramic heater and pressured so as to be fixed on the recording member. However, the image forming apparatus including the fixing device of the heat fixing system consumes a large amount of electricity when heating the toner particles. Therefore, from the viewpoint of energy savings, the adoption of a low-power-consumption fixing device is strongly desired instead of the fixing device of the heat fixing system. Furthermore, the fixing device of the heat fixing system disadvantageously requires a long start-up time until image fixing starts.
In order to address the above problem, a fixing device of a vapor fixing system has been proposed as described, for example, in Patent Document 1. According to the fixing device of the vapor fixing system, a recording paper having unfixed toner particles remaining is inserted into a solvent vapor where the toner particles are dissolved. Therefore, the fixing device of the vapor fixing system consumes less energy than the heat fixing device of the heat fixing system does. However, due to an odor from a liquid and concerns about effects on the human body, the fixing device of the vapor fixing system is not widely used. Meanwhile, an odorless and harmless liquid allowing toner particles to become swollen and then be dissolved so as to be fixed has been developed. As a result, attention is given again to a fixing system using a liquid.
As described, for example, in Patent Document 2, a fixing device using an odorless and harmless toner fixing liquid discloses a method of fixing unfixed toner particles onto a recording member. Specifically, a toner fixing liquid including a softening agent for softening toner particles and a solvent for dispersing or dissolving the softening agent is used. The toner fixing liquid is attached to the recording member having a transferred image in a manner as to be sprayed or dropped, or coated with a roller, etc. Then, toner particles on the recording member are softened and the toner fixing liquid is dried. As a result, the unfixed toner particles are fixed onto the recording member.
Because the fixing device of this system does not require a toner heating process unlike the fixing device of the heat fixing system, it is suitable for achieving reduced power consumption and energy savings. For example, as shown in Patent Document 3, a toner fixing liquid is sprayed onto an intermediate transfer member and then directly transferred and fixed onto a recording member.    Patent Document 1: JP-A-40-10867    Patent Document 2: JP-B2-3290513    Patent Document 3: JP-A-2004-109747    Patent Document 4: JP-A-2006-308781